Sit-Up Board

ABSTRACT

Disclosed herein is a sit-up board. The sit-up board includes a first board ( 110 ), a second board ( 120 ), and a guy cable ( 160 ). At least one tension spring is provided on a lower surface of the first board. At least one extension cable, which is coupled to an end of the tension spring and extends the tension spring, is drawn to the upper surface of the first board along a plurality of guide units provided on the lower surface of the first board. The second board is coupled to the first board via a hinge unit in such a way as to rotate downwards, with a foot support being detachably mounted to the second board. The guy cable passes through ends of the first and second boards, and supports the first and second boards at a predetermined angle. This invention facilitates a wide variety of exercises.

TECHNICAL FIELD

The present invention relates, in general, to a sit-up board and, more particularly, to a sit-up board, which facilitates a wide variety of exercises and has a simple structure.

BACKGROUND ART

Modern people who sit for a long time and do not exercise regularly face an increased risk of ruptured disks or abdominal obesity. In order to solve the problem, various kinds of exercise equipment for treating the spine or strengthening abdominal muscles have been developed.

A handstand machine and a sit-up board are representative of exercise equipment for treating the spine or strengthening abdominal muscle.

The handstand machine is configured to hold a user's ankles and allow the user to do a handstand. The handstand machine is useful to treat the spine and promote blood circulation. However, the handstand machine is problematic in that it is impossible to exercise other body parts. Further, since the volume of the handstand machine is large, it is difficult to store and move. Furthermore, the handstand machine is expensive.

Meanwhile, the sit-up board is exercise equipment which holds two feet so that a user may lie down on the board and do sit-ups without help from others, thus building abdominal muscles. For example, a sit-up board has been proposed in Korean U.M. Registration No. 0308209.

The sit-up board includes a first board 2 and a second board 4. An end of the first board 2 and an end of the second board 4 are hinged to a support shaft 6 which is horizontally disposed at a predetermined height, so that the first and second boards 2 and 4 are linearly coupled to each other. A first support post is provided at a predetermined position on the sit-up board to maintain the support shaft 6 at the predetermined height. The sit-up board also includes a second support post 14 that functions to support a free end of the second board 4 which is not coupled to the first board 2. A first board pushing up part 18 is provided at a predetermined position on the sit-up board, and causes the first board 2 to rotate about the support shaft 6 relative to the second board 4, thus pushing up the first board 2 at a predetermined angle, therefore helping a user to do sit-ups. Further, a foot support 46 is installed at a predetermined position on the second support post 14, and serves to support a user's feet while the user does sit-ups (see, FIG. 1).

The sit-up board constructed as described above is advantageous in that the first board pushing up part 18 lessens the burden on the waist, when a user exercises to strengthen abdominal muscles. However, the conventional sit-up board is disadvantageous in that it is impossible to exercise the abdominal region, the arms, the legs, etc. other than the upper part of the belly.

DISCLOSURE OF INVENTION

1. Technical Problem

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a sit-up board, capable of treating the spine, strengthening the upper part of the belly or the abdominal region, and exercising the arms, the legs, etc.

Another object of the present invention is to provide a sit-up board, which is foldable and is lightweight, thus being easy to store and move.

2. Technical Solution

In order to accomplish the above objects, the present invention provides a sit-up board, including a first board having at least one elastic member provided on a lower surface of the first board, at least one extension cable coupled to an end of the elastic member and extending the elastic member, and a plurality of guide units provided on the lower surface of the first board, so that the extension cable is drawn to an upper surface of the first board along the guide units; a second board coupled to the first board via a hinge unit in such a way as to rotate downwards, with a foot support being detachably mounted to the second board; and a guy cable passing through ends of the first and second boards, and supporting the first and second boards at a predetermined angle.

Such a construction allows spine treatment or the stretching of the waist. Further, this construction allows a user to do sit-ups without help from others, thus strengthening the muscles in the upper part of the belly. By pulling the extension cable, the arm and shoulder muscles can be built.

Both ends of the guy cable are held by a fastening button, and an insertion hole is formed in a central portion of the fastening button so that a stop protrusion provided at each of the ends of the guy cable is inserted into the insertion hole, the insertion hole having a cross shape and being formed such that a central portion of the insertion hole is wide to allow the stop protrusion to be easily inserted into the insertion hole, and a side portion of the insertion hole is narrow to secure the inserted stop protrusion therein, the stop protrusion being provided at two or more places on each of the ends of the guy cable.

Such a construction is capable of lengthening the guy cable held by the fastening button, thus allowing the first and second boards to be laid flat.

The second board includes at least one tension spring provided on a lower surface of the second board, an extension cable coupled to a lower end of the tension spring, and extending the tension spring, and a plurality of guide units provided on the lower surface of the second board, so that the extension cable is drawn to an upper surface of the second board along the guide units, and is fastened to the foot support.

Such a construction allows the extension cable secured to the ankles to be pulled, thus building the abdominal region or leg muscle.

The guide units includes a first guide part installed to be aligned with the elastic member, and a second guide part provided outside the first guide part, and perpendicularly changing a direction of the extension cable coupled to the lower end of the elastic member. In this case, the first guide part includes guide plates supported by at least one support post, and a guide rod rotatably installed between the guide plates, and guiding the extension cable, and the second guide part includes a pair of first guide rods rotatably installed between left and right guide plates, and a pair of second guide rods rotatably installed between front and rear guide plates, and arranged to be perpendicular to the first guide rods.

According to this construction, the extension cable can be easily drawn to the upper surface of the first board, regardless of the direction in which the extension cable is pulled, thus allowing a user to exercise in various directions.

The extension cable of the first board is provided with at least one stop protrusion such that a handle is detachably coupled to the extension cable, and an insertion hole is formed at a predetermined position on the handle such that the stop protrusion is inserted into the insertion hole. Further, a seat is provided at a predetermined position in the insertion hole such that the inserted stop protrusion is seated in and locked to the seat.

According to this invention, the handle is easily detachably mounted to the extension cable, so that it is possible to couple the handle to a desired position of the extension cable, as necessary.

The foot support has a circular shape, and includes a first fastening part jointed by a hinge shaft, and a second fastening part having a rod-shaped locking lug, and a lug holder to prevent upward movement of the locking lug when the locking lug has been seated in the lug holder. In this case, an insertion hole is provided at a predetermined position on the first fastening part such that a head of a fastening bolt of the second board or the stop protrusion provided on each of the ends of the extension cable of the second board is inserted into the insertion hole, the insertion hole having a cross shape and being formed such that a central portion thereof is wide to allow the head of the fastening bolt or the stop protrusion to be easily inserted into the insertion hole, and a side portion is narrow to allow the inserted head of the fastening bolt or the inserted stop protrusion to be seated in or locked to the insertion hole.

According to another embodiment of this invention, each of the first and second boards may comprise a plurality of parts, and the parts may be coupled to each other via coupling rods. Such a construction allows all components to be separated from each other, thus minimizing the volume of the sit-up board when it is stored, moved, or sold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing the construction of a conventional sit-up board;

FIG. 2 is a perspective view of a sit-up board, according to the first embodiment of the present invention;

FIG. 3 is a perspective view of the sit-up board of FIG. 2, when the sit-up board is unfolded;

FIG. 4 is a bottom perspective view of the sit-up board of FIG. 3;

FIG. 5 is an exploded perspective view showing a hinge unit, according to this invention;

FIG. 6 is a perspective view showing a handle, according to this invention;

FIG. 7 is a perspective view showing a foot support, according to this invention;

FIG. 8 is a partially exploded perspective view of a sit-up board, according to the second embodiment of the present invention;

FIG. 9 is a perspective view of a sit-up board, according to the third embodiment of the present invention;

FIG. 10 is a bottom perspective view of the sit-up board of FIG. 9, when the sit-up board is unfolded;

FIG. 11 is a perspective view showing a foot support, according to another modification of this invention; and

FIGS. 12 to 15 are views showing the use of the sit-up board, according to the third embodiment of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a perspective view of a sit-up board, according to the first embodiment of the present invention, FIG. 3 is a perspective view of the sit-up board of FIG. 2, when the sit-up board is unfolded, and FIG. 4 is a bottom perspective view of the sit-up board of FIG. 3.

As shown in the drawings, the sit-up board 100 of this invention includes a first board 110, a second board 120, and a guy cable 160. The first board 110 has the shape of a rectangular plate, and a user's torso rests on the first board 110. The second board 120 is coupled to the first board 110 via a hinge unit 130 to rotate downwards, with the lower part of the body resting on the second board 120. Further, the guy cable 160 penetrates an end of each of the first and second boards 110 and 120, and supports the first and second boards 110 and 120 at a predetermined angle.

A tension spring 112, which is an elastic member, is longitudinally provided along a central portion in the first board 110. Further, three pairs of extension cables 114, 116, and 118 are drawn from left and right sides of the lower surface of the first board 110 to the upper surface thereof, and are spaced apart from each other by a predetermined interval. The extension cables 114, 116, and 118 are coupled to a lower end of the tension spring 112 to extend the tension spring 112. Handles 140 are detachably coupled to ends of the extension cables 114.

As shown in FIG. 4, the extension cables 114, 116, and 118 are drawn along a plurality of guide units, provided on the lower surface of the first board 110, to the upper surface thereof. The guide units include guide plates 112 a, and guide rods 112 b which are rotatably installed between the guide plates 112 a. The guide units are installed at one place at the center, six places on the left side, and six places on the right side of the first board 110, so that the upper, middle, and lower extension cables 114, 116, and 118 are drawn to the upper surface of the first board 110 at regular intervals. Especially, guide bars 112 c each having a guide groove may be additionally provided at moving courses of the upper and lower extension cables 114 and 118.

Likewise, a tension spring 122 is longitudinally provided along a central portion in the second board 120. A pair of extension cables 126 is drawn to the upper surface of the left and right sides of the second board 120. The extension cables 126 are coupled to a lower end of the tension spring 122 and extend the tension spring 122. Foot supports 150 are easily detachably coupled to ends of the extension cables 126. Reference numeral 124 denotes fastening bolts that detachably fasten the foot supports 150 to the second board 120, when a user does sit-ups without help from others.

Similarly to the extension cables of the first board 120, the extension cables 126 of the second board 120 are guided in predetermined courses by guide units. The guide units include guide plates 122 a, and guide rods 122 b that are rotatably installed between the guide plates 122 a. The guide units are provided at one place at the center, two places on the left side, and two places on the right side of the second board 120. Further, guide bars 122 c each having a guide groove 122 d may be additionally provided at moving courses of the extension cables 126.

Cable holes 110 b and 120 b are formed in the ends of the first and second boards 110 and 120, with the guy cable 160 passing through the cable holes 110 b and 120 b. Both ends of the guy cable 160 are held by a fastening button 162. An insertion hole 162 a is formed at a central portion in the fastening button 162 so that stop protrusions 160 a and 160 b provided on both ends of the guy cable 160 pass through the insertion hole 162 a.

The shape of the insertion hole 162 a is similar to a cross shape. Shown in FIG. 2, the central portion of the insertion hole 162 a is wide to allow the stop protrusions 160 a and 160 b to be easily inserted into the insertion hole 162 a, while side portions 162 b of the insertion hole 162 a are narrow to prevent the inserted stop protrusions 160 a and 160 b from being removed from the insertion hole 162 a. Further, a seat may be provided on each side portion 162 b of the insertion hole 162 a.

Since the stop protrusions 160 a, 160 b are provided on two places of each end of the guy cable 160, the length of the guy cable 160 may be appropriately adjusted to correspond to the case where the sit-up board 100 is set up at an angle to the ground surface (see, FIG. 2) or the case where the sit-up board 100 is laid flat (see, FIG. 3). Further, cable guide slots 110 a and 120 a are formed in four places on the first and second boards 110 and 120 to guide the guy cable 160 (see, FIG. 4). Such a construction allows the first and second boards 110 and 120 to be stably in close contact with the ground surface, when the sit-up board 100 is unfolded, as shown in FIG. 3.

FIG. 5 is an exploded perspective view showing the hinge unit 130 coupling the first and second boards 110 and 120 to each other. As shown in the drawing, hinge brackets 132 and 134 are provided on respective ends of the first and second boards 110 and 120, and a hinge shaft 136 is inserted into the hinge brackets 132 and 134 so that the first board 110 is hinged to the second board 120. Further, an interference edge 132 a is provided on a side of each of the hinge brackets 132, thus preventing the first and second boards 110 and 120 from rotating upwards.

FIG. 6 is a perspective view showing the handle 140, according to this invention. As shown in the drawing, the shape of the handle 140 is similar to a circular shape. A grip 142 is provided at a position in the handle 140. Further, an insertion hole 144 is provided at another position in the handle 140 such that a stop protrusion 114 a, 116 a, 118 a provided on an end of the extension cable 114, 116, 118 is inserted into the insertion hole 144.

The shape of the insertion hole 144 is similar to a cross shape. When shown from FIG. 6, a central portion 144 a of the insertion hole 144 is wide to allow the stop protrusion 114 a, 116 a, 118 a to be easily inserted into the insertion hole 144. Conversely, when shown from FIG. 6, side portions 144 b of the insertion hole 144 are narrow to prevent the inserted stop protrusion 114 a, 116 a, 118 a from being undesirably removed from the insertion hole 144. Such an insertion hole 144 of the handle 140 allows the handle 140 to be easily detached from an end of the extension cable 114, 116, 118. Thus, it is possible to detachably couple one handle to a desired one among several extension cables 114, 116, and 118.

FIG. 7 is a perspective view showing the foot support 150, according to this invention. As shown in the drawing, the foot support 150 has a fastening structure like a handcuff or the like. In a detailed description, the foot support 150 includes first and second fastening parts. The first fastening part is jointed by a hinge shaft 156. The second fastening part includes a rod-shaped locking lug 152 and a lug holder 154. After the locking lug 152 is seated in the lug holder 154, the lug holder 154 prevents upward movement of the locking lug 152. In this case, the circular foot support 150 itself has elasticity, so that it is easy to open or close the foot support 150 when necessary. However, once the locking lug 152 has been seated in the lug holder 154, the foot support 150 does not open, even if a force is applied in a direction from an inside to an outside of the second fastening part.

Further, an insertion hole 158 is formed at a predetermined position on the first fastening part, so that a stop protrusion provided on an end of each extension cable 126 is inserted into the insertion hole 158. The shape of the insertion hole 158 is similar to a cross shape. A central portion 158 a of the insertion hole 158 is wide to allow the stop protrusion to be easily inserted into the insertion hole 158. Conversely, side portions 158 b of the insertion hole 158 are narrow to prevent the inserted stop protrusion from being undesirably removed from the insertion hole 158. Since the insertion hole 158 has the same construction as the insertion hole 144 of the handle 140, the insertion hole 158 will not be described in detail herein.

FIG. 8 is a partially exploded perspective view of a sit-up board, according to the second embodiment of the present invention. Those elements common to both the first embodiment and the second embodiment will carry the same reference numerals. The sit-up board of the second embodiment is characterized in that each of first and second boards 210 and 220 comprises a plurality of parts that are coupled to each other via coupling rods 212, 222. In this case, each of the coupling rods 212 and 222 may have an assemblable structure. If the sit-up board is manufactured in this way, it is possible to minimize the volume of the sit-up board during the storage or sale of the sit-up board.

Rod passing pipes (not shown) may be additionally provided in the first and second boards 210 and 220 so that the coupling rods 212 and 222 pass through the rod passing pipes. Further, lower ends of the coupling rods 212 and 222 passing through the rod passing pipes are supported by closed end members of the first and second boards 210 and 220, so that the undesirable removal of the coupling rods 212 and 222 is prevented.

Meanwhile, when the guy cable 160 is lengthened to arrange the first and second boards 210 and 220 levelly, the removal of the coupling rods 212 and 222 is prevented by the guy cable 160.

When the first and second boards 210 and 220 are manufactured through plastic injection molding, manufacturing costs are reduced, and the weight of the sit-up board is reduced, so that it is easy to move the sit-up board to another place. Further, when each of the first and second boards 210 and 220 comprises several parts, the strength of the sit-up board is greater than that of the sit-up board having the first and second boards 210 and 220 that are integrated with each other.

The operation of this invention constructed as described above will be described below.

First, when a user desires to do sit-ups for strengthening the upper part of the belly or to exercise the upper body, including the arms and the shoulders, the operation of the sit-up board will be described with reference to FIGS. 2 to 4. To this end, the hinge unit 130 is adjusted to locate the first and second boards 110 and 120 at a pre-determined angle. In order to maintain this state, the guy cable 160 is fastened to the fastening button 162. At this time, the first stop protrusions 160 a provided at ends of the guy cable 160 are inserted into the insertion hole 162 a of the fastening button 162. Thereafter, the first stop protrusions 160 a are seated in the side portions 162 b so as to prevent the first stop protrusions 160 a from being removed from the insertion hole 162 a.

Next, the head of each fastening bolt 124 of the second board 120 is inserted into the central portion 158 a of the insertion hole 158 of each foot support 150 shown in FIG. 7, and is seated in the side portion 158 b, prior to the fastening bolt 124 being secured by a nut provided on a lower surface of the second board 120. After both ankles are inserted into the corresponding foot supports 150, each locking lug 152 is elastically fastened to an associated lug holder 154. Once each locking lug 152 has been seated in the lug holder 154, each foot support 150 is not opened even if a force is applied in a direction from the inside to the outside of the fastened part, that is, a user lifts up his or her feet, because each lug holder 154 prevents the upward movement of the locking lug 152.

As such, after both ankles have been secured into the foot supports 150, a user's torso rests on the first board 110. In such a state, the user may repeatedly raise his or her torso. Thus, the user can do sit-ups easily without help from others, and thereby build muscles in the upper part of the belly.

Moreover, when the torso rests on the first board 110, and the handles 140 are pulled, the tension spring 112 is extended, in conjunction with the extension cables 114 coupled to the handles 140. Thereby, it is possible to exercise the arm and shoulder muscles. The extension cables 114 are drawn to the upper surface of the first board 110 along the guide units that are provided in the central portion and on left and right sides of the lower surface of the first board 110. Such a construction is advantageous in that it is possible to exercise the arms and the shoulders in various directions, according to the positions of the pulled extension cables 114, 116, and 118.

Since the handles 140 are easily detachably coupled to ends of the extension cables 114, 116, and 118, it is possible to easily couple the handles 140 to desired extension cables 114, 116, 118. Thus, only one pair of handle 140 is required, thus reducing manufacturing costs, and affording convenience to a user when the sit-up board is moved or stored.

The sit-up board operated as described above is helpful in treating the spine, stretching the waist, and promoting blood circulation. Further, the sit-up board of this invention facilitates exercises for building muscles in the upper part of the belly through sit-ups and exercises for the arms and the shoulder in various directions.

Meanwhile, when a user desires to build the abdominal region or leg muscle by lifting the legs, the first stop protrusions 160 a of the guy cable 160 are unfastened from the fastening button 162. The second stop protrusions 160 b of the guy cable 160 are fastened to the fastening button 162, so that the first and second boards 110 and 120 are laid flat, as shown in FIG. 3. At this time, the interference edges 132 a are formed on the hinge brackets 132 provided on a side of the hinge unit 130, thus preventing the first and second boards 110 and 120 from rotating upwards.

In such a state, both feet are inserted into the corresponding foot supports 150. Next, after a user sits on the sit-up board, lies on his/her back or lies face down, the user lifts his or her legs. At this time, the tension spring 122 is extended, in conjunction with the extension cables 126 coupled to the foot supports 150. Thereby, it is possible to build abdominal muscles or various leg muscles. In this case, the extension cables 126 are drawn to the upper surface of the second board 120 along the guide units which are provided in the central portion and on left and right sides on the lower surface of the second board 120. The sit-up board constructed as described above is advantageous in that it is possible to do exercises to strengthen abdominal and leg muscles.

When a user finishes exercising and desires to store or move the sit-up board, the second board 120 rotates about the hinge unit 130 relative to the first board 110. Thus, the sit-up board is advantageous in that it occupies a small space during storage, and is easy to move.

Particularly, according to the second embodiment shown in FIG. 8, each of the first and second boards 210 and 220 comprises a plurality of parts that are coupled to each other via the coupling rods 212 and 222. Such a construction allows all components to be separated from each other, thus minimizing the volume of the sit-up board when it is stored, moved, or sold.

Hereinafter, the third embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. 9 is a perspective view of a sit-up board, according to the third embodiment of this invention, and FIG. 10 is a bottom perspective view of the sit-up board shown in FIG. 9, when the sit-up board is unfolded.

As compared to other embodiments of this invention, the sit-up board of the third embodiment is characterized in that tensions springs 312 are installed on both left and right sides on the lower surface of a first board 310. Such a construction affords a firm structure, in comparison with the sit-up board having one tension spring, and in addition, allows the left and right parts of the body to be separately exercised.

Further, the sit-up board of this embodiment is provided with a pair of extension cables 316 that function to extend the tension springs 312, and a second board 320 is not provided with a tension spring. This simplifies the construction of the sit-up board, thus simplifying a manufacturing process and reducing manufacturing costs.

Reference numeral 400 of FIG. 9 denotes a pulling strap which is held by a user, when the spine is treated, sit-ups are done, or the torso is raised. Support balls 410 are provided at several places on the pulling strap 400. In order to secure the support balls 410 to the pulling strap 400 at regular intervals, a screw hole is formed at a pre-determined position on each support ball 410, so that a screw 412 is tightened into the corresponding screw hole (see, partially enlarged portion C of FIG. 9).

Referring to FIG. 9, the sit-up board includes handles 340. A grip 342 is provided at a position on each handle 340. Further, an insertion hole 344 is provided at another position on each handle 340 such that a stop protrusion 316 a provided on an end of each extension cable 316 is inserted into the insertion hole 344 (see, partially enlarged portion A of FIG. 9).

The insertion hole 344 has a size and a shape allowing each stop protrusion 316 a to be easily inserted therein. Further, a semi-elliptical part 344 a is provided at a position in the insertion hole 344. The size and the shape of the semi-elliptical part 344 a are determined so that the semi-elliptical part 344 a holds the stop protrusion 316 a without preventing the undesirable removal of the inserted stop protrusion 316 a. A seat 344 b is provided at an upper position of the semi-elliptical part 344 a (see, partially enlarged portion B of FIG. 9). The insertion hole 344 of each handle 340 allows the handle 340 to be easily detached from one end of the extension cable 316, thus allowing one handle to be coupled to a desired position of each extension cable 316.

Meanwhile, a plurality of stop protrusions 316 a may be provided on each extension cable 316, thus permitting various exercises. That is, a stop protrusion 316 a, which is provided at the first position on the upper surface of the first board 310, serves to prevent the extension cable 316 from being inserted into the first board 310. Further, each foot support 350 is held by the first stop protrusion 316 a of the extension cable 316, thus allowing a user to exercise the legs (see, FIG. 13). Furthermore, stop protrusions 316 a, which are provided at the second and third positions on the upper surface of the first board 310, may be used according to a user's position or height (see, FIGS. 12 and 14). Meanwhile, the method of coupling the stop protrusions 316 a to the extension cables 316 may adopt the method of coupling the support balls 410 to the pulling strap 400.

Referring to FIG. 10, coupling rods 372 and the tension springs 312, which are accommodated in passing pipes 370 and 312 a, respectively, are provided on the lower surface of the first board 310 comprising a plurality of parts, thus enhancing the durability of the product and providing a good appearance. Further, paper tubes may be provided in the passing pipes 312 a accommodating the tension springs 312 therein, thus minimizing noise generated when the tension springs 312 are extended.

The portion encircled in FIG. 10 is a partially enlarged view of a guide unit. Referring to the drawing, the guide unit includes first guide parts 380 and second guide parts 390. The first guide parts 380 are installed to be aligned with the corresponding tension springs 312. The second guide parts 390 are provided outside the corresponding first guide parts 380, thus perpendicularly changing the direction of the extension cables 316 coupled to ends of the tension springs 312.

Each of the first guide parts 380 includes guide plates 382 supported by four support posts 384. Further, a guide rod 386 is rotatably installed between the guide plates 382, and guides each extension cable 316.

After each extension cable 316 passes through an associated first guide part 380, the direction of the extension cable 316 is perpendicularly changed such that the extension cable 316 is guided by each second guide part 390, thus being drawn to the upper surface of the first board 310. Each of the second guide parts 390 includes a pair of first guide rods 396 which are rotatably installed between left and right guide plates 392 when shown from FIG. 10, and a pair of second guide rods 398 which are rotatably installed between front and rear guide plates 394 and are provided under the first guide rods 396, when shown from FIG. 10, to be perpendicular to the first guide rods 396.

Each of the second guide parts 390 constructed as described above allows the extension cable 316 to be easily drawn to the upper surface of the first board 310, regardless of the direction in which the extension cables 316 are drawn. Thus, it is possible to exercise in various directions.

FIG. 11 is a perspective view showing a foot support 350, according to another modification of this invention. Referring to the drawing, the foot support 350 includes a body 356 having an insertion hole 358. Hook and pile pieces 352 and 354 of a Velcro are provided at respective opposite ends of the body 356.

Each fastening bolt 324 provided on the second board 320 of FIG. 9 is inserted into the insertion hole 358 of each foot support 350. Since the construction of the insertion hole 358 is equal to that of the insertion hole 344 of the above-mentioned handle 340, the insertion hole 358 will not be described in detail herein. Reference numeral 358 a denotes a semi-elliptical part 358 a, and reference numeral 358 b denotes a seat.

The hook and pile pieces 352 and 354 serve to fasten the ankle to the body 356 of each foot support 350. The Velcro is advantageous in that they may be used regardless of the size of the ankle.

Meanwhile, referring to FIG. 15, the foot supports 350 may be installed on the first board 310. To this end, one or more pairs of fastening bolts 324 may be detachably provided on the first board 310. In order to use such a construction, a user fastens the user's feet to the corresponding foot supports 350, and lies face down. In this case, the user's torso rests on the second board 320. In such a state, by lifting the torso up and down, the user can do a back-extension exercise. Further, as shown in FIG. 15, when two or more pairs of fastening bolts 324 are provided at different positions, it is possible to install the foot supports 350 according to the user's height.

FIGS. 12 to 15 are views showing the use of the sit-up board, according to the third embodiment of this invention. Hereinafter, the features and operation of the sit-up board, according to the third embodiment, constructed as described above, will be described with reference to FIGS. 9 through 15.

When a user intends to do sit-ups to build the upper part of the belly or exercise the torso including the arms and shoulder, the operation of the sit-up board will be described with reference to FIG. 12. First, a hinge unit 330 is adjusted to locate the first and second boards 310 and 320 at a predetermined angle. In order to maintain such a state, a guy cable 360 is secured to a fastening button 362.

In such a state, the head of each fastening bolt 324 secured by a nut (not shown) inside the second board 320 is inserted into the insertion hole 358 of each foot support 350 of FIG. 11, prior to being seated in the seat 358 b. Next, both ankles are inserted into the corresponding foot supports 350. The foot supports 350 are adjusted using the hook and pile pieces 352 and 354 provided on the foot supports 350, according to the size of the ankles.

After the ankles are secured to the foot supports 350, the torso rests on the first board 310. Afterwards, by repeatedly raising the torso, a user can easily do sit-ups without help from others and thereby build muscles in the upper part of the belly.

Further, when the torso rests on the first board 310 and the handles 340 are pulled, the tension springs 312 (see, FIG. 10) are extended in conjunction with the extension cables 316 coupled to the corresponding handles 340, thus exercising muscles in the arms and shoulder. The extension cables 316 are drawn to the upper surface of the first board 310 along the guide unit provided on the lower surface of the first board 310. At this time, the second guide parts 390 constructed as described above allow a user to exercise in various directions.

The sit-up board of this invention operated as described above is helpful in treating the spine, stretching the waist, and promoting blood circulation. Further, the sit-up board is advantageous in that exercises for building muscles in the upper part of the belly through sit-ups or exercise for the arms or shoulders can be done in various directions.

Meanwhile, when one desires to build the abdominal region or leg muscles by lifting the legs, as shown in FIG. 12, first stop protrusions 360 a of the guy cable 360 are detached from the fastening button 362, and thereafter, second stop protrusions 360 b of the guy cable 360 are fastened to the fastening button 362. Thereby, the first and second boards 310 and 320 are horizontally unfolded.

In such a state, as described above, the foot supports 350 are secured to the extension cables 316. If necessary, it is possible to secure the foot supports 350 using the first or second stop protrusions which are positioned on the upper surface of the first board 310. Next, both feet are fastened using the hook and pile pieces 352 and 354 (see, FIG. 11). In such a state, a user sits down, lies face up or face down, and afterwards lifts up the user's legs.

At this time, the tension springs 312 (see, FIG. 10) are extended in conjunction with the extension cables 316 coupled to the foot supports 350, thus building muscles in the abdominal region or various leg muscles. In this case, the extension cables 316 are drawn along the guide unit provided on the lower surface of the first board 310 to the upper surface of the first board 310.

Further, as shown in FIG. 14, while a user stands on or repeatedly sits down on and stands up on an end of the first board 310, he or she pulls the handles 340 coupled to the extension cable 316 in various directions, thus variously exercising.

The sit-up board constructed as described above is advantageous in that it has a simpler structure that those of the first and second embodiments, and allows a user to do exercises for building muscles in the abdominal region and leg muscles. Since other advantages and operation of the third embodiment are equal to or similar to those of the first and second embodiments, they will not be described herein in detail.

FIG. 15 shows the state where a user does a back-extension exercise using the sit-up board according to this invention. As shown in FIG. 15, the foot supports 350 are fastened to the first board 310 using the fastening bolts 324. A user's feet are secured to the foot supports 350, prior to the user lying face down. At this time, the user's torso is positioned on the second board 320. In such a state, by lifting the torso up and down, the user does the back-extension exercise. Such a back-extension exercise causes the lower part of the back and the abdominal muscles to be evenly strengthened, thus preventing back pain.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. For example, a tension spring is used as the elastic member herein, but various elastic members including rubber or the like may be used in place of the tension spring.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides a sit-up board, which can be used for multiple purposes, for example, spine treatment, building the upper part of the belly or the abdominal region, and exercises for the back (back-extension), the arms, the legs, and other areas.

Further, the sit-up board of this invention is foldable and lightweight, so that it is easy to store and move to another position. Furthermore, the sit-up board of this invention is advantageous in that it has a simple structure, enables various exercises, and is inexpensive. 

1. A sit-up board, comprising: a first board, comprising: at least one elastic member provided on a lower surface of the first board; at least one extension cable coupled to an end of the elastic member, and extending the elastic member; and a plurality of guide units provided on the lower surface of the first board, so that the extension cable is drawn to an upper surface of the first board along the guide units; a second board coupled to the first board via a hinge unit in such a way as to rotate downwards, with a foot support being detachably mounted to the second board; and a guy cable passing through ends of the first and second boards, and supporting the first and second boards at a predetermined angle.
 2. The sit-up board according to claim 1, wherein the elastic member comprises a tension spring.
 3. The sit-up board according to claim 1, wherein both ends of the guy cable are held by a fastening button, and an insertion hole is formed in a central portion of the fastening button so that a stop protrusion provided at each of the ends of the guy cable is inserted into the insertion hole, the insertion hole having a cross shape and being formed such that a central portion of the insertion hole is wide to allow the stop protrusion to be easily inserted into the insertion hole, and a side portion of the insertion hole is narrow to secure the inserted stop protrusion therein, the stop protrusion being provided at two or more places on each of the ends of the guy cable.
 4. The sit-up board according to claim 1, wherein the extension cable of the first board is provided with at least one stop protrusion such that a handle is detachably coupled to the extension cable, and an insertion hole is formed at a predetermined position on the handle such that the stop protrusion is inserted into the insertion hole, with a seat being provided at a predetermined position on the insertion hole such that the stop protrusion is seated in and locked to the seat.
 5. The sit-up board according to claim 1, wherein the second board comprises: at least one tension spring provided on a lower surface of the second board; an extension cable coupled to a lower end of the tension spring, and extending the tension spring; and a plurality of guide units provided on the lower surface of the second board, so that the extension cable is drawn to an upper surface of the second board along the guide units, and is fastened to the foot support.
 6. The sit-up board according to claim 1, wherein the foot support has a circular shape, and comprises: a first fastening part jointed by a hinge shaft; and a second fastening part comprising: a rod-shaped locking lug; and a lug holder to prevent upward movement of the locking lug when the locking lug has been seated in the lug holder, wherein an insertion hole is provided at a predetermined position on the first fastening part such that a head of a fastening bolt of the second board or the stop protrusion provided on each of the ends of the extension cable of the second board is inserted into the insertion hole, the insertion hole having a cross shape and being formed such that a central portion thereof is wide to allow the head of the fastening bolt or the stop protrusion to be easily inserted into the insertion hole, and a side portion is narrow to allow the inserted head of the fastening bolt or the inserted stop protrusion to be seated in and locked to the insertion hole.
 7. The sit-up board according to claim 1, wherein the foot support comprises: a body; and hook and pile pieces of a Velcro provided on opposite ends of the body, wherein an insertion hole is provided at a predetermined position on the body such that a head of a fastening bolt of the second board or the stop protrusion provided on each of the ends of the extension cable of the second board is inserted into the insertion hole, with a seat being provided at a predetermined position in the insertion hole such that the inserted stop protrusion is seated in and locked to the seat.
 8. The sit-up board according to claim 1, wherein each of the first and second boards comprises a plurality of parts, the parts being coupled to each other via coupling rods.
 9. The sit-up board according to claim 1, wherein the guide units comprise: a first guide part installed to be aligned with the elastic member; and a second guide part provided outside the first guide part, and perpendicularly changing a direction of the extension cable coupled to the lower end of the elastic member, wherein the first guide part comprises: guide plates supported by at least one support post; and a guide rod rotatably installed between the guide plates, and guiding the extension cable, and the second guide part comprises: a pair of first guide rods rotatably installed between left and right guide plates; and a pair of second guide rods rotatably installed between front and rear guide plates, and arranged to be perpendicular to the first guide rods.
 10. The sit-up board according to claim 1, wherein the extension cable of the first board is provided with at least one stop protrusion such that a handle is detachably coupled to the extension cable, and an insertion hole is formed at a predetermined position on the handle such that the stop protrusion provided at each of the ends of the extension cable is inserted into the insertion hole, the insertion hole having a cross shape and being formed such that a central portion thereof is wide to allow the stop protrusion to be easily inserted into the insertion hole, and a side portion thereof is narrow to allow the inserted stop protrusion to be seated in and locked to the insertion hole.
 11. The sit-up board according to claim 1, further comprising: one or more pairs of foot supports detachably secured to the first board. 